The present invention relates to the digital color printer art. It finds particular application in conjunction with a method and apparatus for implementing anti-counterfeiting measures in personal computer-based digital color printers, and will be described with particular reference thereto. However, it should be appreciated that the present invention may also find application in conjunction with other types of digital color marking systems and applications where anti-counterfeiting measures are implemented.
It is known to implement anti-counterfeiting measures in high-end electrophotographic marking devices, such as xerographic copiers, which anti-counterfeiting measures typically require relatively large amounts of on-board memory and processing power. Electrophotographic marking is performed by exposing an image representation of a desired document onto a substantially uniformly charged photoreceptor. In response to the image representation, the photoreceptor discharges so as to create an electrostatic latent image of the desired document on the photoreceptor's surface. Toner particles are then deposited onto the latent image so as to form a toner image. The toner image is then transferred from the photoreceptor onto a substrate such as a sheet of paper. The transferred toner image is then fused to the substrate, usually using heat and/or pressure. The surface of the photoreceptor is then cleaned of residual developing material and recharged in preparation for the production of another image. Electrophotographic marking can be used to produce color images by repeating the above process once for each color of toner that is used to make the composite color image.
There has been a proliferation of low-end marking devices, such as digital color printers that are primarily used with personal computers (PCS), and that are now capable of generating very high quality color renderings of image representations at a relatively low cost. This has led to a growing concern over the possibility of using such low-end digital color printers for illicitly reproducing or otherwise generating currency, checks, stock certificates, legal documents, and other printed documents that are not legally reproducible. Obviously, any reproductions of these documents are counterfeit and illegal.
Low-end marking devices typically do not include a large amount of on-board memory or processing capability. Thus, it is not feasible to incorporate the same relatively expensive, hardware intensive, anti-counterfeiting measures found in high-end electrophotographic marking devices into such low-end, PC-based, digital color printers. Accordingly, it is considered desirable to develop a new and improved, low-cost, method and apparatus for implementing anti-counterfeiting measures in PC-based digital color printers, that meets the above-stated needs and overcomes the foregoing difficulties and others while providing better and more advantageous results.